Lucy McGough wrote:What, are YOU uncertain whether or not you are currently dreaming? I don't think that that's a common uncertainty.

Probably not, but it IS a common technique for helping one with lucid dreaming. You keep asking yourself if you're SURE you're not dreaming. Meant to make you both aware of HOW you know you're not dreaming, and to make sure it carries over to your subconscious so you ask that in your dreams. So, it's not an unheard of issue.